1. Field of the Invention
This invention relates to processing of a substrate in making a disk to be used in a fixed disk disk drive. More particularly, it relates to using a vacuum deposition machine to sputter etch an inner annular region or landing zone of a substrate prior to laser texture of the landing zone.
2. Description of the Prior Art and Related Information
The overall cost and performance of a contemporary fixed-disk disk drive, such as a magnetic hard disk drive, depend significantly on the cost and performance of each magnetic disk within the drive.
The cost of manufacturing magnetic disks depends in part on the cost and efficiency of operation of various machines used to carry out numerous processes involved in manufacturing the disks. These processes include texturing processes. Typically, one machine is used for "full-surface" texturing and another machine is used for landing zone texturing. An example of a machine for landing zone texturing is a standalone laser texturing machine which includes a rotating and translating spindle that rotates a substrate while a stationary pulsed laser beam is directed at the rotating substrate causing bumps to be formed in the landing zone of the substrate.
The standalone machine typically laser textures one substrate at a time and its throughput may be severely limited by factors such as the substrate handling time. Also, the cost of the laser texturing machine may constitute a significant portion of the overall cost of manufacturing the disks.
The manufacturing of magnetic disks also typically involves the use of a stationary vacuum deposition machine. (In this art, a stationary vacuum deposition machine is commonly called a stationary sputtering machine, and the two different terms are used interchangeably herein.). An alternate machine is an in-line sputtering machine. Either type of machine is used to, among other things, deposit a succession of thin film layers on a substrate. The thin film layers may include an underlayer, a magnetic layer, and a carbon overcoat layer. A typical stationary sputtering machine includes a series of stations. The series of stations includes a load station, a plurality of sputtering stations, a cooling station, a heating station, and an unload station. Each station has a per-stage processing time of typically approximately 5 to 7 seconds. The sputtering stations are used to sputter the succession of thin film layers on a substrate; typically, both sides of the substrate are sputtered with the succession of thin film layers. Among the series of stations, a plurality of spare stations are also usually included. The cost of a sputtering machine adds a significant portion to the overall cost of manufacturing the disks.
The performance of a fixed-disk disk drive depends in part on structures that affect the startup of operation of the drive. In a typical disk drive, a slider lands in the landing zone when the disk drive is powered down. Texturing of the landing zone reduces the effective contact area between the slider and the surface of the landing zone thereby reducing the static friction forces ("stiction") that must be overcome to separate the slider from the surface of the landing zone when the disk drive is powered on. Such a reduction of static friction forces improves the performance of the disk drive.
Researchers in the field have attempted to explain and control the formation of bumps in a landing zone of a substrate such as a nickel-phosphorous (Ni-P) plated substrate. For example, the publication "Experimental and Theoretical Studies of Bump Formation During Laser Texturing of Ni-P Disk Substrates" by Tam et al., discloses a model for the formation of sombrero-shaped bumps based on competition between temperature gradients ("thermocapillary effect") and surface composition gradients ("chemicapillary effect"). The chemicapillary effect is a surface composition gradient which produces a surface tension gradient; the surface tension gradient controls the flow of material from low to high tension. The publication discloses that because of the competition between thermocapillary and chemicapillary effects, either sombrero-shaped bumps or rim only bumps are formed by a Gaussian shaped laser beam depending on the laser parameters chosen.
A need exists in the art to reduce the costs of manufacturing the disks. Additionally, a need exists in the art to improve the control of the height of bumps formed in a landing zone of a substrate.